The invention relates to an electrical drive, in particular for an electrical tool having a motor with a rotor and a stationary stator, which has a coil arrangement, and having a motor controller for controlling the motor, with the motor controller being configured for passing current through the coil arrangement in order to produce an excitation field, with the coil arrangement having a plurality of coil winding sections, and with each coil winding section having a plurality of coil sections.
A drive such as this is known from DE 10 2007 040 725 A1.
The known drive is an electrical machine having a rotor with permanent magnet excitation and having a stator which is fitted with a polyphased winding and can be operated on the one hand in a relatively low rotation speed range, and on the other hand in a relatively high rotation speed range. For this purpose, provision is made to disconnect parts of the stator winding, or to switch between series connection and parallel connection.
In addition to normal operation, this is intended to allow so-called weak-field operation in a relatively high rotation speed range.
Different rotation speed ranges can therefore in principle be provided with one electrical machine. However, it has been found that, in this case, weak-field operation may involve increase thermal loading. Operating modes such as these can therefore frequently be used only temporarily, for example as so-called boost functions.
It is also known that the rotation speed level of an electrical drive, in particular of an EC motor, can be influenced by regulating the supply voltage. In this case, in principle, there may be a proportional relationship between the achievable operating rotation speed and the supply voltage.